Turn off the water supply valve behind the toilet
Flush the toilet to empty the tank and bowl
Check the water supply line for leaks and tighten or replace it if needed
Inspect the fill valve and adjust or replace it if it is leaking
Check the flapper for wear, warping, or debris and replace it if necessary
Inspect the flush valve seal and replace it if damaged
Tighten the tank bolts if water is leaking between the tank and bowl
Replace the tank-to-bowl gasket if it is worn or cracked
Check the wax ring at the base of the toilet if water is leaking from the floor
Remove the toilet and replace the wax ring if needed
Reinstall the toilet and tighten the mounting bolts evenly
Turn the water back on and test for leaks
Replace the toilet if cracks are found in the tank or bowl